Photographic emulsions

ABSTRACT

This application describes a green sensitive gelatino silver halide photographic emulsion which comprises, substantive thereto, at least one magenta yielding color former and which comprises in sensitizing amount a cyanine dye of the general formula:   WHEREIN R1 represents a halogen atom or a lower alkyl or amino group, R and R3 are the same or different and represent lower alkyl groups containing at least two carbon atoms, one of R2 and R4 is a sulphoalkyl group of the formula -(CH2)nSO3H where n is an integer from 1 to 6, and the other of R2 and R4 is the same or different said sulphoalkyl group or is an alkyl, hydroxyalkyl, aralkyl, carboxy-substituted aralkyl, or carboxy-substituted alkyl group, an acylsulphamoyl alkyl group of the formula (CH2)nSO2NHCOR8, or an alkyl or aralkyl sulfamoyl alkyl group of the formula -(CH2)nSO2NHR9 where n in the last two formulas is an integer from 1 to 6, R8 is an alkyl group and R9 is an alkyl or an aralkyl or amino group, R5 represents a hydrogen or halogen atom or an alkyl or amino group, R6 represents a hydrogen or halogen atom or a trifluoromethyl, cyano or alkoxycarbonyl group, and X is an anion.

United States Patent 72] inventors Konrad Jerzy Bannert;

Douglas James Fry, both of llford, Essex, England [21] Appl. No. 741,854 [22] Filed July 2, 1968 [45] Patented Oct. 26, 1971 [73] Assignee llford Limited Essex, England [32] Priority July 4, 1967 [33] Great Britain [31] 30,778/67 [54] PHOTOGRAPHIC EMULSIONS 3 Claims, No Drawings [52] US. Cl. 96/106, 96/ 100 [51] Int; Cl. G03c 1/10 [50] Field ofSearch ..96/l00, 106

[56] References Cited UNITED STATES PATENTS 3,255,012 6/1966 Glockner et al. 96/100 3,348,949 10/1967 Bannert et al. 96/106 X FOREIGN PATENTS 505,979 5/1939 England 96/106 ir 555i; fiarni nr Norman Gl Torchin 7 Assistant Examiner.lohn L. Goodrow Attorney-Cushman, Darby & Cushman ABSTRACT: This application describes a green sensitive wherein R represents a halogen atom or a lower alkyl or amino group, R and R are the same or different and represent lower alkyl groups containing at least two carbon atoms, one of R and R, is a sulphoalkyl group of the formula -(Cl-l ),,SO H where n is an integer from 1 to 6, and the other of R and R, is the same or different said sulphoalkyl group or is an alkyl, hydroxyalkyl, aralkyl, carboxy-substituted aralkyl, or carboxysubstituted alkyl group, an acylsulphamoyl alkyl group of the formula -(CH ),,SO NHCOR or an alkyl or aralkyl sulfamoyl alkyl group of the formula -(CH ),,SO NHR, where n in the last two formulas is an integer from 1 to 6, R is an alkyl group and R, is an alkyl or an aralkyl or amino group, R represents a hydrogen or halogen atom or an alkyl or amino group, R represents a hydrogen or halogen atom or a trifluoromethyl, cyano or alkoxycarbonyl group, and X is an anion.

PHOTOGRAPHIC EMULSIONS This invention relates to photographic emulsions and in particular to gelatino silver halide emulsions having substantive thereto color formers and an improvement in or modification of our British Pat. Ser. No. 1,111,903.

Gelatino silver halide emulsions which comprise substantive color formers are used in color photography and usually three such emulsion layers are used in a color photographic assembly, one layer not being color sensitized, one of the other layers being green sensitized by the presence therein of an optical sensitizers which cause the emulsion to be sensitive to a comparatively narrow waveband of light in the green region of the spectrum and the third layer being red sensitized by the presence therein of optical sensitizers which cause the emulsion to be sensitive to a comparatively narrow waveband of light in the red region of the spectrum In the emulsion making process optical sensitizers are usually added to the emulsion during the formation of the silver halide grains and become adsorbed onto these grains. Color formers are added to the emulsion at a later stage of the emulsion making process, very often just prior to coating the emulsion onto a support. It has been found that the addition of the color formers to the emulsion tends to strip off the adsorbed optical sensitizers from the silver grains, thus altering considerably the degree and range of color sensitivity of the emulsion. However some classes of optical sensitizers are more resistant than others to stripping when color formers are incorporated into the emulsion, and it has been discovered that this applies to certain of the cyanine dyes described and claimed in British Pat. No. 1,1 11,903.

Therefore according to the present invention there is provided a green sensitive gelatino silver halide photographic emulsion which comprises, substantive thereto at least one magenta yielding color former and which comprises in sensitizing amount a cyanine dye of the general formula I:

wherein R represents a halogen atom or a lower alkyl or amino group, R and R are the same or different and represent lower alkyl groups containing at least two carbon atoms, one of R and R is a sulphoalkyl group of the formula -(CH ,),,SO H where n is an integer from one to six, and the other of R and R is the same or different said sulphoalkyl, group or is an alkyl, hydroxyalkyl, aralkyl, carboxy-substituted aralkyl, or carboxy-substituted alkyl group, an acylsulphamoyl alkyl group of the formula (CH ),,SO NHCOR or an alkyl or aralkyl sulphamoyl alkyl group of the formula -(CH ),,SO NHR where n in the last two formulae is an integer from one to six, R is an alkyl group and R is an alkyl or an aralkyl or amino group, R represents a hydrogen or halogen atom or an alkyl or amino group, R represents a hydrogen or halogen atom or a trifluoromethyl, cyano or alkoxycarbonyl group, and X is an anion.

When R and R each represent a sulphoalkyl group, i.e. (CH ),,SO H the dye is usually isolated in the form of the anhydro hydroxide compound.

By lower alkyl groups are meant groups containing one to six carbon atoms. Examples of hydroxyalkyl groups are hydroxymethyl and hydroxyethyl. An example of aralkyl is benzyl. An example of carboxy-substituted aralkyl is carboxybenzyl. An example of carboxy-substituted alkyl is carboxymethyl. An example of an alkoxycarbonyl group is methoxycarbonyl. An example of an acylsulphamoyl alkyl group is y- (acetylsulphamoyl) propyl. An example of alkyl sulphamoyl alkyl is ethyl sulphamoyl butyl. An example of aralkyl sulfamoyl alkyl is benzyl sulfamoyl ethyl.

The two following dyes have been found to be of especial value in the invention: ('1-ethyl-3-sulphopropyl-5- trifluoromethyl-6-chloro-2-benzimidazole) 1,3-di-ethyl-5- chloro-Z-benzimidazole) trimethincyanine iodide which has the formula ll:

and l-ethyl-3-sulphopropyl-5-trifluoromethyl-6-bromo-2- benzimidazole) l,3-di-ethyl-5-chloro-2-benzimidazole) trimethincyanine iodide which has the formula III:

The following examples will serve to illustrate the invention:

EXAMPLE 1 The dye of formula II (0.20 g. per gm. mole of silver halide) dissolved in 2-methoxyethanol, was added to a melted gelatino-silver iodobromide emulsion. A mixture (3:1 molecular ratio) of color formers of structures A and B was wetted with methanol and dissolved in normal potassium hydroxide solution and added to the dyed emulsion. The emulsion was divided into two parts. The first part was coated immediately and the second part after keeping for 3 hours at a temperature of 37 C. After exposure through a yellow filter (transmitting substantially no light of wavelengths shorter than 510 nm.) the film strips were processed through a color negative processing sequence. The relative log speed of the trial coated immediately was 3.22 measured at a density of 0.1 above fog density and the relative log speed of the emulsion kept for 3 hours before coating was 3. l 8. The speed figures show that a negligible change in emulsion speed was produced by keeping the molten emulsion for 3 hours before coating, which demonstrates that no desorption of the sensitizing dye had taken place.

EXAMPLE 2 The dye of formula III was tested as in example 1 using 0.2

g. dye per gm. mole of silver halide and using the same mixture of color formers. The relative log speed of the trial coated immediately was 3.60 and the relative log speed of the emulsion coated after standing for 3 hours was 3.36.

EXAMPLE 3 The dye formula IV (which follows) was tested as in example 1, using the same quantity of dye. The relative log speed of the trial coated immediately was 3.34 and the speed of the trial coated after 3 hours was 3.18.

lh b YgHs N N c1 c1 C-CH=CHCH=C F30 CF; 1): (011,);

S03 SOaH IV EXAMPLE 4 The dye of formula V was tested as in example 1, using the same quantity of dye. The relative log speed of the trial coated immediately was 3.00 and the speed of the trial coated after 3 hours was 2.96.

(lhHr 1 21 5 N N H;C on

/CCH=CHCH=C F|O CF3 I (EH91 (CHz)3 S03 S 03H V I EXAMPLE 5 The dye of formula VI was tested as in example I, using the same quantity of dye. The relative log speed of the emulsion coated immediately was 3.23 and the speed of the emulsion coated after standing for 3 hours was 3.16.

$3H5 (E2115 Br Br /CCH=CHCHC F 30 0 Fa i (311 l Hzh S03" so Na VI EXAMPLE 6 The dye of formula VII was tested as in example I, using the same quantity of dye. The relative log speed of the emulsion coated immediately was 3.31 and the speed of the emulsion coated after standing for 3 hours was 3.24.

(33115 (IJZH5 N /N H C C=CHCH=CHC Fae Cl I N f (6H2): C Ha SO H VII EXAMPLE 7 The dye of formula VIII was tested as in example 1 but using 0.3 g. dye per 1 gm. mole of silver halide. The relative log speed of the emulsion immediately after coating was 3.26 and the speed of the emulsion coated after standing for 3 hours was 3.04.

( zls S0311 VIII All the foregoing'examples show that silver halide emulsions containing magenta color formers and sensitized to green by dyes of the general formula I show negligible or only small changes in speed when subjected to a period of standing before coating. The following examples 8 and 9 show that emulsions containing dyes of similar structure not possessing a sulphoalkyl group suffer much greater changes in speed when they are stood before coating. Both the dyes used in examples 8 and 9 produced similar speeds in emulsions to the dyes used in examples 1-7 when tested in an emulsion free from color formers.

EXAMPLE 8 The dye of formula IX was tested as in example I, using the same quantity of dye. The relative log speed of the emulsion coated immediately was 2.64 and the speed of the emulsion coated after standing for 3 hours was 2.21. The low speed of the emulsion coated immediately shows that some of the dye had been stripped in the short interval of time between the addition of the color formers and the coating and drying of the emulsion.

2 5 1 2 5 N N 01 o1 C=CHCH=CH-C I F 0 F; i I 0:115 0:115 IX EXAMPLE 9 The dye of formula X was tested as in example I. The relative log speed of the emulsion coated immediately was 2.15 and the speed of the emulsion coated after standing for 3 hours was 1.89. As for the dye used in example 8, these speed figures show that severe stripping occurs almost instantaneously when the color formers are added to the emulsion and further stripping takes place as the emulsion is kept.

We claim as our invention:

1. A green sensitive gelatino silver halide photographic emulsion which comprises, substantive thereto, at least one magenta yielding color former which is a pyrazolone derivative and which comprises in sensitizing amount a cyanine dye of the general formula:

wherein R represents a halogen atom or a lower alkyl or amino group, R and R are the same or different and represent lower alkyl groups containing at least two carbon atoms, one 2. 5 1 .81 i ylma kzl 9 22 9f h fqi a-lfifi H where n is an integer from 1 to 6, and the other of R and R is the same or different said sulphoalkyl group or is an alkyl, hydroxyalkyl, aralkyl, carboxy-substituted aralkyl, or carboxysubstituted alkyl group, an acylsulphamoyl alkyl group of the formula -(CH ),,SO,NHCOR or an alkyl or aralkyl' sulphamoyl alkyl group of the formula -(CH ),,SO NHR where n in the last two formulas is an integer from 1 to 6 R is an alkyl group and R is an alkyl or an aralkyl or amino group, R represents a hydrogen or halogen atom or an alkyl or amino group, R represents a hydrogen or halogen atom or a trifluoromethyl, cyano or alkoxycarbonyl group, and X is an anion.

2. A green sensitive gelatino silver halide photographic emulsion which comprises, substantive thereto, at least one magenta yielding color former and which comprises in sensitizing amount (1-ethyl-3-sulphopropyl-5-trifluoromethyl-6- chloro-2-benzimidazole) 1,3-diethyl-5-chloro-2- benzimidazole) trimethincyanine iodide.

3. A green sensitive gclatino silver halide photographic emulsion which comprises substantive thereto, at least one magenta yielding color former and which comprises in sensitizing amount (l-ethyl-3-sulphopropyl-5-trifluoromethyl-6- bromo-Z-benzimidazole) 1,3-diethyL5-chloro-2- benzimidazole) trimethincyanine iodide, 

2. A green sensitive gelatino silver halide photographic emulsion which comprises, substantive thereto, at least one magenta yielding color former and which comprises in sensitizing amount (1-ethyl-3-sulphopropyl-5-trifluoromethyl-6-chloro-2-benzimidazole) (1,3-diethyl-5-chloro-2-benzimidazole) trimethincyanine iodide.
 3. A green sensitive gelatino silver halide photographic emulsion which comprises substantive thereto, at least one magenta yielding color former and which comprises in sensitizing amount (1-ethyl-3-sulphopropyl-5-trifluoromethyl-6-bromo-2-benzimidazole) (1,3-diethyl-5-chloro-2-benzimidazole) trimethincyanine iodide. 